This document claims priority and contains subject matter related to Japanese Patent Application No. 2002-195185, filed with the Japanese Patent Office on Jul. 3, 2002, the entire contents of which are hereby incorporated by reference.
The apparatus and method as well as materials used in the resin sealing play important roles in electronic device packaging. A method is known for forming a layer of sealant resin on the surface of a semiconductor wafer substrate provided with a protruded electrode, in which several steps are proceeded such as forming first a coating layer at the tip of the protruded electrode, forming a layer of raw sealant resin over the substrate so as the tip of the protruded electrode be exposed afterwards, hardening the layer to form a sealant resin layer, and removing the coating layer (Japanese Laid-Open Patent Application No. 7-161764).
In a further method previously known, a metal mold is formed to arrange therein a semiconductor wafer substrate, sealant resin tablets, and temporary films for preventing the resin from sticking to the mold. By subsequent heating under pressurization, the resin is spread over the wafer substrate to form a sealant resin layer (Japanese Laid-Open Patent Application No. 2001-55432). In this method the sealant resin is then polished to expose the tip portion of electrodes.
As another example, the method has been attracting attention recently, in that a semiconductor wafer substrate is provided thereon with semiconductor devices each having protruded electrodes called post electrodes which are formed so as the tips thereof be exposed, and that this semiconductor wafer substrate as-is can be subjected to resin sealing process without being cut into chips. In addition, the noted semiconductor devices are disclosed as chip-size package or wafer level chip-size package (Japanese Laid-Open Patent Application No. 2000-260910).
In the resin sealing process for fabricating the chip-size package, sealant resin layers can be formed by spin-coating raw resin layer or by heat molding under pressurization in a metal mold, for example. In the spin-coating method for forming the sealant resin layer, however, a drawback is that additional steps must be taken for forming a coating layer at the tip of the protruded electrode, as noted earlier, thereby complicating the process. In addition, other drawbacks are encountered in the method of spin coating such as wasteful use of resinous material and difficulty in precise control of raw sealant resin layer especially in the vicinity of protruded electrodes.
In the method using metal molds, disadvantages are that various kinds of molds have to be provided corresponding to each wafer substrate with different specification, and that polishing steps are required for exposing tip portions of electrodes, to thereby increase manufacturing costs.
Furthermore, there encountered a difficulty in handling the thus prepared sealant resin layer, in which chipping off of the resin layer may arise during dicing steps or conveying steps following the carving out of the semiconductor devices.